Table 4

Logistic regression on SHS exposure with interaction with the 2009 smoke-free policy and gender/socioeconomic factors, 2006–2011*

Factor	SHS exposure in homes		SHS exposure in workplaces
Factor	OR	95% CI	OR	95% CI
Model 1: interaction with gender
The 2009 policy (reference: 2006–2008)
Year 2009–2011	0.67	0.61 to 0.74	0.45	0.37 to 0.54
Gender (reference: female)
Male	0.79	0.73 to 0.86	2.02	1.80 to 2.27
Gender × the 2009 policy interaction (reference: female × year (2009–2011))
Male × (year 2009–2011)	1.10	0.98 to 1.23	1.13	0.92 to 1.39
Model 2: interaction with education
The 2009 policy (reference: 2006–2008)
Year 2009–2011	0.82	0.75 to 0.89	0.53	0.46 to 0.60
Education (reference: undergraduate or above)
High school	2.03	1.87 to 2.20	2.40	2.15 to 2.68
Elementary school or below	2.51	2.19 to 2.88	2.85	2.32 to 3.50
Education × the 2009 policy interaction (reference: undergraduate or above × (year 2009–2011))
High school × (year 2009–2011)	0.87	0.79 to 0.96	0.84	0.71 to 1.01
Elementary school or below × (year 2009–2011)	0.71	0.60 to 0.85	0.89	0.65 to 1.22
Model 3: interaction with income
The 2009 policy (reference: 2006–2008)
Year 2009–2011	0.71	0.62 to 0.81	0.52	0.42 to 0.65
Monthly income (reference: ≥NT$80 000)
NT$60 000–NT$80 000	1.02	0.91 to 1.14	1.09	0.88 to 1.35
NT$20 000–NT$60 000	1.12	1.04 to 1.22	1.27	1.06 to 1.53
≤NT$20 000	1.20	1.05 to 1.36	1.21	0.91 to 1.61
Missing	1.07	0.96 to 1.18	1.06	0.89 to 1.26
Income × the 2009 policy interaction (reference: ≥NT$80 000 × year 2006–2008)
NT$60 000–NT$80 000 × (year 2009–2011)	1.11	0.92 to 1.34	0.90	0.67 to 1.20
NT$20 000–NT$60 000 × (year 2009–2011)	1.03	0.89 to 1.19	0.88	0.70 to 1.10
≤NT$20 000 × (year 2009–2011)	0.92	0.76 to 1.12	0.95	0.69 to 1.32
Missing × (year 2009–2011)	0.84	0.71 to 1.01	0.92	0.73 to 1.17

*Other covariates included age, gender, employment, marital status, county smoking rate and trend.
SHS, secondhand smoke.